Known is an electrophotographic type printer provided with a process cartridge. The process cartridge includes a drum cartridge having a photosensitive drum, and a developing cartridge having a developing roller for supplying toner to the photosensitive drum. The process cartridge is detachably mountable in the printer.
Such a printer has a known configuration such that the developing roller of the developing cartridge contacts the photosensitive drum to supply the toner to the photosensitive drum when an image is formed, and is separated from the photosensitive drum not to supply the toner to the photosensitive drum when an image is not formed.
For example, the developing cartridge has right and left side walls on which engagement protrusions are respectively provided. The drum cartridge has right and left side walls on which front nipping levers and rear nipping levers are respectively provided. Each engagement protrusion is nipped by the front nipping lever and the rear nipping lever, so that the developing cartridge is brought into contact with and separated from the photosensitive drum.
With this configuration, the rear nipping levers respectively press the engagement protrusions of the developing cartridge toward the photosensitive drum. Thus, the developing cartridge normally contacts the photosensitive drum. Further, to separate the developing cartridge from the photosensitive drum, the front nipping levers respectively press the engagement protrusions of the developing cartridge forward against the pressing force from the rear nipping levers.